A silicon photomultiplier (SiPM) is an array of passively quenched Geiger-mode avalanche photodiodes (APD) for detecting impinging photons. SiPM can provide information about certain parameters, such as the time of the impingement event, the energy associated with the event, and the position of the event within the detector. These parameters can be determined through processing algorithms applied to the analog signals generated by the SiPM. Some conventional SiPMs can produce very fast signals, which provides a high degree of timing accuracy.
SiPMs provide certain advantages over conventional photomultiplier tubes (PMTs), and are therefore being used in many applications, including Positron Emission Tomography (PET) for medical imaging. These advantages include better photon detection efficiency (i.e., a high probability of detecting an impinging photon), compactness, ruggedness, low operational voltage, insensitivity to magnetic fields and low cost.
However, the transmission of analog signals from the SiPM for processing can present problems. For example, due to its small size, many SiPMs often are used in a given application. Therefore, many individual signal lines may be required to carry the signals, which increases complexity in readout electronics, manufacturing complexity and cost. Furthermore, the quality of the signal is more likely to deteriorate as the size and complexity of the SiPM increases.